TBF overhead parameter parsing.

For TBF, implement overhead parameter parsing.

The change is ABI (Application Binary Interface) backward compatible
with older kernels, but will first have effect from kernel 2.6.24.
Signed-off-by: Jesper Dangaard Brouer <hawk@comx.dk>
Signed-off-by: Stephen Hemminger <stephen.hemminger@vyatta.com>

tc/q_tbf.c

@@ -26,7 +26,8 @@
 static void explain(void)
 {
 	fprintf(stderr, "Usage: ... tbf limit BYTES burst BYTES[/BYTES] rate KBPS [ mtu BYTES[/BYTES] ]\n");
-	fprintf(stderr, "               [ peakrate KBPS ] [ latency TIME ]\n");
+	fprintf(stderr, "               [ peakrate KBPS ] [ latency TIME ] ");
+	fprintf(stderr, "[ overhead BYTES ]\n");
 }
 
 static void explain1(char *arg)
@@ -45,6 +46,7 @@ static int tbf_parse_opt(struct qdisc_util *qu, int argc, char **argv, struct nl
 	__u32 ptab[256];
 	unsigned buffer=0, mtu=0, mpu=0, latency=0;
 	int Rcell_log=-1, Pcell_log = -1;
+	unsigned short overhead=0;
 	struct rtattr *tail;
 
 	memset(&opt, 0, sizeof(opt));
@@ -130,6 +132,15 @@ static int tbf_parse_opt(struct qdisc_util *qu, int argc, char **argv, struct nl
 				return -1;
 			}
 			ok++;
+		} else if (matches(*argv, "overhead") == 0) {
+			NEXT_ARG();
+			if (overhead) {
+				fprintf(stderr, "Double \"overhead\" spec\n");
+				return -1;
+			}
+			if (get_u16(&overhead, *argv, 10)) {
+				explain1("overhead"); return -1;
+			}
 		} else if (strcmp(*argv, "help") == 0) {
 			explain();
 			return -1;
@@ -171,6 +182,7 @@ static int tbf_parse_opt(struct qdisc_util *qu, int argc, char **argv, struct nl
 	}
 
 	opt.rate.mpu      = mpu;
+	opt.rate.overhead = overhead;
 	if (tc_calc_rtable(&opt.rate, rtab, Rcell_log, mtu) < 0) {
 		fprintf(stderr, "TBF: failed to calculate rate table.\n");
 		return -1;
@@ -179,6 +191,7 @@ static int tbf_parse_opt(struct qdisc_util *qu, int argc, char **argv, struct nl
 
 	if (opt.peakrate.rate) {
 		opt.peakrate.mpu      = mpu;
+		opt.peakrate.overhead = overhead;
 		if (tc_calc_rtable(&opt.peakrate, ptab, Pcell_log, mtu) < 0) {
 			fprintf(stderr, "TBF: failed to calculate peak rate table.\n");
 			return -1;
@@ -252,6 +265,10 @@ static int tbf_print_opt(struct qdisc_util *qu, FILE *f, struct rtattr *opt)
 	}
 	fprintf(f, "lat %s ", sprint_time(latency, b1));
 
+	if (qopt->rate.overhead) {
+		fprintf(f, "overhead %d", qopt->rate.overhead);
+	}
+
 	return 0;
 }